1. Field of the Invention
This invention relates to hydroxyalkyl quaternary ammonium carboxylate compounds used as catalysts for promotion of reactions involving organic isocyanates, as in the production of polyisocyanurates and polyurethanes.
2. Prior Art
The use of certain quaternary ammonium compounds in the production of polyurethane resins is disclosed in prior patents, for example, in U.S. Pat. Nos. 2,779,689 and 2,981,700. The activity of these compounds depends upon their decomposition to liberate the corresponding tertiary amines. Typical of these suggested quaternary ammonium compounds are the neutral salts formed by reaction of a tertiary amine, such as N-methyl morpholine, with acetic anhydride. The quaternary salts of this type, in general have lower catalytic activity than the tertiary amines from which these are derived.
Fabris et al in U.S. Pat. No. 3,726,816 lists a number of quaternary ammonium bases stated to be known in the art as catalysts in polyurethane reactions, including among these benzyl trimethyl ammonium hydroxide and heterocyclic quaternary ammonium hydroxides such as N-methyl pyridinium hydroxide and morpholinium bases. The patent also mentions the corresponding alkoxides, aryloxides and aralkoxides as exemplified, among others named, by benzyl trimethyl ammonium methoxide and ethoxide, and tetramethyl ammonium phenoxide. The patent proposes the use of these quaternary ammonium bases in polyurethane formulations in conjunction with compounds effective in neutralizing the quaternary base, so as to produce low odor polyurethane foams.
Erner in U.S. Pat. No. 3,010,963 discloses the preparation of quaternary hydroxyalkyl bases of diazabicyclo-octane and of imidazole by reacting the corresponding diazine or diazole with alkylene oxide and water. The obtained quaternary hydroxide can be further reacted with mineral acid or certain named organic acids to produce salts. Thus, the patent describes the production of N-N' bishydroxypropyl diazabicyclo-octane dihydroxide and conversion of the same to salts by reaction respectively with sulfuric, cresylic, salicyclic and phosphoric acids. The sulfates and phosphates are stated to have powerful inhibitory action on the growth of certain micro-organisms such as yeasts, molds and lactobacilli. The patent does not describe any specific use for the organic acid salts. In another example of the patent, the quaternary hydroxide obtained by reaction of 2-methyl imidazole with propylene oxide and water, is converted to the acetate salt, which was tested as a polymerization promoter in polyurethane foam reactions when used in association with the theretofore known highly active diazabicyclooctane catalyst.
Lambert et al, U.S. Pat. No. 3,108,975 is concerned with the production of water blown polyurethane foams from polyether polyols having predominantly secondary hydroxyl end groups. The patent proposes for use as catalysts in this reaction, optionally in the presence of known tertiary amine catalysts, certain basic compounds such as hydroxides of alkali or alkaline earth metals, or of fully substituted quaternary ammonium radicals; or salts of the foregoing. Among the quaternary ammonium radicals listed are those of N-methyl pyridinium, benzyltrimethyl ammonium and trimethyl cyclohexyl ammonium. Among possible salts the patent lists generally alkoxides, phenoxides, carboxylates, carbonates and others. The patent contains no specific example using the disclosed quaternary ammonium salts as catalysts or otherwise in the production of polyurethanes nor in other polyisocyanate reactions.
In copending application, Ser. No. 377,446 filed July 9, 1973 now abandoned, methods are disclosed for synthesis of certain acyclic quaternary hydroxyalkyl ammonium alkoxides and phenoxides useful, among other suggested purposes as catalysts for making polyurethane and polyurethane-polyisocyanurate foams; their use for such purpose is claimed in a simultaneously filed companion application Ser. No. 377,447, now U.S. Pat. No. 3,892,687, issued July 1, 1975.
In copending application Ser. No. 490,946 filed July 23, 1974, now U.S. Pat. No. 3,993,652, issued Nov. 23, 1976, phenoxides of certain cyclic quaternary ammonium bases containing an hydroxyalkyl group attached to the hetero N, are disclosed and claimed as catalysts in reactions involving organic isocyanates, such as in the formation of polyisocyanurates, polyurethanes, and polyurethane-polyisocyanurate resins.